carlstedt



June 25, 1957 B. J. CARLSTEDT CALCULATOR Filed July 6, 1955 United States The object of the present invention is to produce a calculating machine which is of simple design and construction and which can be given an attractive appearance and manufactured and sold at an extremely low cost.

Another object of the invention is to produce a calculating machine which may be used for mixed calculation operations, viz. addition as well as subtraction without any additional manipulations.

Still another object of the invention is to produce-a calculation machine that may be manufactured of a minimum of details which may be moulded of plastic or stamped of metal sheet.

The calculating machine which acts without any mechanical power source may briefly be described as comprising in combination a platform upon which a plurality of longitudinal series of consecutive digits are imprinted, an endless flexible belt, preferably of plastics for each series of digits, said belts being movable longitudinally over said platform and having circular openings to conform with the digits imprinted on the platform and formed to lit a finger tip, two stationary bars extending transversely over the platform immediately beyond the first and last digit of each series to form a stop for the movement of the belts by a finger tip, an assembly of individually rotatable pulleys at each end of said platform, over each of which pulleys a belt is looped and the pulleys of at least one of said assemblies being each provided with cylindrical projections adapted to fit in said holes in the belt and spaced in conformity therewith, a series of digits corresponding to that on the platform being imprinted on the peripheral surface of said projections, said numbered pulleys being provided with a ten transfer mechanism of the type admitting the pulleys to rotate in both directions, while advancing the pulley next adjacent to the left one position when moved one turn in either direction, and a series of zero setting wheels keyed to a common rotatable shaft parallel with the axis of the numbered pulleys and movable transversely thereto so as to selectively bring the zero setting wheels out of or into engagement with its own numbered pulley or two adjacent pulleys to rotate the same at rotation of said common shaft, and each of said numbered pulleys has a recess corresponding to the zero position of the respective pulley and arranged when positioned opposite a zero setting wheel to permit the latter to rotate freely without actuating the numbered pulley.

One important advantage of my invention resides in the fact that while using a simple calculation mechanism known per se you can perform practically all calculating operations common to ordinary office work, since as mentioned in the foregoing, the calculator according to my invention may be used for addition as well as for subtraction, and for this purpose an inverted series of consecutive digits may be imprinted besides each of the before mentioned vertical series of digits.

In the following description an embodiment of my invention is more fully described and illustrated in the accompanying drawing.

atent 1 In the drawing:

Figure 1 is a top plan view of the assembled calculator with an. outer case and some belts removed and some parts of the remaining belts and the numbered pulleys broken away, and Figure 2 is a side elevational view of the calculator in Fig. 1 still having the outer case removed.

A frame consisting of two longitudinal parallel parts 1 support at one end an assembly 2 of numbered pulleys 6 and at the opposite end an assembly of freely rotatable pulleys 3. A pair of transverse parts 4 connects the frame parts 1 and supports a platform 5 located in a plane in flush with the periphery of the pulleys 6 and 3. The platform 5 has in this case five longitudinal series of digits from 0 to 9 imprinted thereon between the pulleys 6 and 3. Two transverse frames 7 and 8 are placed at the ends of the series of digits to serve on one hand as indication which transverse row of digits is to be read on the numbered pulleys 6 and on the other hand as a stop when operating the calculator as will be described in the followmg.

A flexible endless belt 9 preferably made of flexible plastics or rubber is passed over each series of digits on the platform and over its own pulleys 6 and 3. The belt 9 has evenly spaced round holes 10 corresponding to the spacing of the digits on the platform 5 and on the numbered pulleys 6. Said holes 10 are dimensioned to fit a finger tip, by which the belts are to be moved and said frames 7 and 8 serve as stops for the finger tip. In order to prevent the imprinted digits to be defaced by the wear of the finger tip, when moving the belts, said holes may be provided with a bottom of transparent material, preferably integral with the belt material.

To secure movement of the numbered pulleys 6 by the belts 9, the pulleys are provided with cylindrical projections 11 spaced in correspondence with the holes 10. Consecutive digits are imprinted on the peripheral surface of said projections 11, corresponding to the series of digits on the platform.

In the embodiment shown the transmission between adjacent numbered pulleys, which acts to advance a pulley one position at each complete turn of the adjacent pulley, includes an internal transmission. wheel 8, arranged so that it does not prevent the movement of the numbered wheel next to the left. This permits mixed modes of calculation namely subtraction and addition, without any adjustment.

For re-setting the numbered wheels to zero a zero-resetting device consists of a shaft 12 supporting wheels 13, arranged each to engage to adjacent numbered pulleys 6. The shaft 12 extends beyond the frame 1 and may be operated by a hand wheel 14. Each of the numbered pulleys 6 has a suitably positioned recess corresponding in shape to the wheels 13. The Zero setting is accomplished by turning the hand wheel 14, whereby the numbered pulleys 6 are rotated until the recesses 15 are positioned opposite the wheels 13, whereafter the respective wheel 13 does not further actuate the zero positioned numbered pulleys 6. The hand wheel is continuously turned until all numbered wheels are reset to zero. The shaft 12 is slidably journalled in slots that are formed in brackets 16, and is spring biased away from the numbered pulleys.

The calculator is used in the following way:

In adding two or more numbers, e. g. 18 and 33 a finger tip is placed in the hole showing the digit 8 in the belt 9' to the right and is moved downwardly to the digit 0 where it comes into contact with the frame 7. The tens denominational digit 1 is registered in the same way by placing the finger tip in the hole showing the digit of the belt 9" next to the left and moving the same downwardly to the frame 7. Then the number 18 will be readable in the transverse row designated A immediately in front of the frame 8. In adding the number 33 the finger tip is successively placed-in the'hole showing thedigit'3 in the respective belts 9 and 9" and is moved downwardly as above described. The total 51 may then be read at line A, in this manner an arbitrary number of adding operations may be performed. In subtracfion-thebeltsare moved in opposite direction and an invertedjseries of digits may beimprinted'beside, the previous series pref erably of different colour. Thus. thewdig'it 9 'in thefirst series corresponds 'to inthe inverted series; The'fingers tip is to bemoved into contact with theopposite frame 8.

The ,belts are preferably made of flexible plastics, rubber, etc. 7

'WhatI claim is:

A calculator comprising. in combination a platform upon which aplurality of'longitudinal series of consecutive digits are imprinted, an endless -flexible ,belt, preferably of plasticsjfor each series of digits, said beltsbeing movable longitudinally over said platform and having circular openings spaced to conform with the digits imprinted on the platform and formed to fit a finger tip, two stationary bars extending transversely over the platform immediately beyond the first and last digit of each series to form a stop for the movement of the belts by a finger tip, an assembly of individually rotatable pulleys at each end of said platform, over each'of'which pulleys abelt,

is looped and the pulleys of at least one of said assembly being-each provided with cylindrical "projections adapted to fit into said holes in the belt and spaced in conformity therewith, a series of digits corresponding to that on the platform being imprinted on the peripheral surface of said projections, said numbered pulleys being provided with a ten transfer mechanism of the type admitting the pulleys to rotate in both directions, while advancing the pulley next adjacent to the left one positio when moved one turn in either direction, and a series of zero setting wheels key to a mmonrotat bl ,shaftparallel with the axis of the numbered pulleys and movable transversely thereto so as toselectively bringthe'zero setting-wheels out of or into engagement 'with'its own numbered pulley or two adjacent pulleys to rotate the same at rotation of said common shaft, and each of said numbered pulleys has a recess corresponding to the zero position of the respective pulley and arranged when positioned opposite a zero setting wheel topermit-thelatter to rotate-freely without actuating the numbered pulley.

References Cited in the *file: of this patent UNITED STATES PATENTS 1,109,378 Ward ,Sept. '1, 1914 1,257,926 Poole Feb. 26, 1918 1,494,633 Corell May 20,1924 

